In high frequency switches for the mobile radio sector, frequently very high RF amplitudes occur, resulting in reliability problems and high generation of harmonics. The design of an RF switch considers these high amplitudes with different measures. RF transistors in high frequency switches or in RF switches typically have to be designed with very large width. This results in a large number of transistor fingers. Typically between the transistor fingers, the RF voltages are of a similar amount and hence the field strengths are low. Nevertheless, the transistor fingers at an edge, in particular the outermost diffusion region, experiences very high field strengths. As an example, a full RF voltage in an outermost diffusion region is opposed by an RF voltage of zero volt in the adjacent substrate. Naturally, this leads to very high field strengths, high stress at this location and damages of the RF transistors.